diamond shape: keep aspect when checking against minimum ht/wd

[muzimuzhi]

Motivation for this change

Currently, when a diamond shape is enlarged when checking against minimum height/width, the shape aspect is not kept. This PR fixes the problem.

Example

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}

\begin{document}
% shape aspect is initially 1 
\begin{tikzpicture}[nodes={diamond, draw}]
  \node[minimum width=50pt] {x};
  \node[minimum height=50pt] at (2,0) {x};
\end{tikzpicture}
\end{document}

Checklist

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• Code changes are licensed under GPLv2 + LPPLv1.3c
• Documentation changes are licensed under FDLv1.2

[muzimuzhi]

Hmm, pgfmanual reads "the aspect (set by /pgf/aspect/) is a recommendation" for shapes diamond and cylinder.

pgf/doc/generic/pgf/text-en/pgfmanual-en-library-shapes.tex

Lines 112 to 115 in 85d2c38

	\begin{key}{/pgf/aspect=\meta{value} (initially 1.0)}
	The aspect is a recommendation for the quotient of the width and the
	height of a shape. This key calls the macro |\pgfsetshapeaspect|.
	\end{key}

Though the relation between /pgf/shape aspect and /pgf/aspect is not explicitly documented, the above doc suggests what this PR tries to fix is a documented "feature". I still think that minimum height/width has higher precedence than shape aspect is strange.

Therefore this PR may end in one of two ways:

1. Take it as a documented feature and maybe document the relation between /pgf/shape aspect and /pgf/aspect.
2. Change the precedence for both diamond and cylinder, which is certainly a breaking change.

[hmenke]

Unfortunately, we can't do that. What we can do, however, is change the default value for shape aspect to unset and use it if the user explicitly sets a value.

[muzimuzhi]

Please review if the current implementation is "what we can do". If so, I will do the same for shapes cylinder and cloud.

Also can the aspect staff common in libs shapes.geometric and shapes.symbols be moved to a separate file, probably named sth ends with shapes.common.code.tex?

Feels like we can only add features if there's a crack in the manual wall. :)

---

Examples, new

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}

\begin{document}
\tikzset{nodes={diamond, draw}, baseline=0pt}

\def\demo#1{%
  \def\tmp{#1}%
  \ifx\tmp\empty default\else \texttt{#1}\fi:
  \begin{tikzpicture}[style/.expanded={#1}]
    \node[minimum width=50pt] {x};
    \node[minimum height=50pt] at (2,0) {x};
  \end{tikzpicture}
}

\demo{}\par
\demo{shape aspect=none}

\foreach \v in {1, 2, .5} {
  \foreach \k in {shape aspect, aspect} {
    \demo{\k=\v}\qquad
  }\par
}
\end{document}

[hmenke]

Why the special none value? I would have just left it empty.

[hmenke]

If the default was empty the code could be simplified (untested).

Suggested change

	\ifx\pgf@lib@temp\pgf@nonetext
	\pgfkeys{/pgf/aspect=1}%
	\else
	\pgfkeys{/pgf/aspect=#1}%
	\fi
	\pgfkeyssetvalue{/pgf/shape aspect}{#1}%
	\pgfqkeys{/pgf}{aspect/.expanded=\pgfutil@ifxempty\pgf@lib@temp{1}{#1}}%
	\pgfkeyssetvalue{/pgf/shape aspect}{#1}%

Same for the other conditionals.

[hmenke]

On 2026-06-15 a more comprehensive testsuite was introduced for PGF/TikZ. This tests all new contributions against the examples extracted from the manual and checks whether anything has changed to avoid regressions. Since this pull request was opened before that, these tests were not run automatically. I have run l3build check on the result of the merge of this pull request branch into master. The result can be found below.

Tip

Your pull request might have failed some tests. This does not mean that your contribution will be rejected. In fact, depending on the changes you propose, it might even be expected that some tests fail, however, this needs to be evaluated carefully.

Failed tests

• pdftex

  • config-examples

    • pgfmanual-en-library-decorations
    • pgfmanual-en-library-er
    • pgfmanual-en-library-shapes
    • pgfmanual-en-tikz-graphs
    • pgfmanual-en-tikz-matrices
    • pgfmanual-en-tikz-shapes
• latexdvips

  • config-examples

    • pgfmanual-en-library-decorations
    • pgfmanual-en-library-er
    • pgfmanual-en-library-shapes
    • pgfmanual-en-tikz-graphs
    • pgfmanual-en-tikz-matrices
    • pgfmanual-en-tikz-shapes
• latexdvisvgm

  • config-examples

    • pgfmanual-en-library-decorations
    • pgfmanual-en-library-er
    • pgfmanual-en-library-shapes
    • pgfmanual-en-tikz-graphs
    • pgfmanual-en-tikz-matrices
    • pgfmanual-en-tikz-shapes
• luatex

  • config-examples

    • pgfmanual-en-library-decorations
    • pgfmanual-en-library-er
    • pgfmanual-en-library-shapes
    • pgfmanual-en-tikz-graphs
    • pgfmanual-en-tikz-matrices
    • pgfmanual-en-tikz-shapes
• xetex

  • config-examples

    • pgfmanual-en-library-decorations
    • pgfmanual-en-library-er
    • pgfmanual-en-library-shapes
    • pgfmanual-en-tikz-graphs
    • pgfmanual-en-tikz-matrices
    • pgfmanual-en-tikz-shapes